Season's first tropical storm possible to brush East Coast around July 4

National Hurricane Center

A system of rain and thunderstorms off the coast of Florida could become Tropical Storm Arthur this week.

A system of rain and thunderstorms off the coast of Florida could become Tropical Storm Arthur this week. (National Hurricane Center)

Scott Dance, The Baltimore Sun

A rainy system off the coast of Florida could become Tropical Storm Arthur and sweep up the East Coast late this week into the weekend.

The National Hurricane Center expects a 60 percent chance that shower and thunderstorm activity over the Bahamas will organize into Tropical Storm Arthur within 48 hours, and 80 percent chances it will do so within the next five days.

It's too early for the center to suggest any forecast cone showing any storm's possible trajectory, but forecasting models predict the system being pulled up the coast. It could brush North Carolina's Outer Banks, Ocean City and Cape Cod from late this week through the weekend.

"A tropical depression is likely to form by mid-week while the system moves slowly southwestward and then turns northward and northeastward near the southeastern United States coast," hurricane center forecasters wrote.

An Air Force Reserve reconnaissance aircraft could investigate the system Monday afternoon, according to the hurricane center.

With no tropical storms formed yet this year, a month into hurricane season, it is the first time since 2004 without an Atlantic tropical cyclone in May or June. But the developing system suggests we won't go as long without a tropical storm as in that year, when the first named system didn't develop until the end of July.